Implement Value.__format__

Author: NoureldinYosri

test/test_value.py

@@ -279,3 +279,13 @@ def test_pick_roundtrip() -> None:
             x = value * unit
             s = pickle.dumps(x)
             assert x == pickle.loads(s)
+
+
+def test_format() -> None:
+    x = 0.4234324 * tu.ns
+    assert f'{x:0.2f}' == '0.42 ns'
+    assert f'{x:e}' == '4.234324e-01 ns'
+
+    x = 42.235 * tu.GHz
+    assert f'{x:0.2f}' == '42.23 GHz'
+    assert f'{x:0.1e}' == '4.2e+01 GHz'

tunits/core/cython/with_unit.pyx

@@ -704,6 +704,9 @@ cdef class WithUnit:
         self.display_units.__setstate__(pickle_info['display_units'])
         self.base_units.__setstate__(pickle_info['base_units'])
 
+    def __format__(self, spec: str) -> str:
+        return self.value.__format__(spec) + ' ' + str(self.unit)
+
 _try_interpret_as_with_unit = None
 _is_value_consistent_with_default_unit_database = None
 def init_base_unit_functions(